The present disclosure relates to a pivot structure of scissors formed by fitting a pivot into a through-hole formed in an intermediate portion of each of first and second blade bodies to pivotably connect the first and second blade bodies together, and more particularly to a pivot structure suitable for hairdressing scissors.
FIG. 1 illustrates a pivot structure of known hairdressing scissors. The pivot structure is formed by fitting a pivot 3 into through-holes 7 and 9 formed in an intermediate portion of each of a first blade body 1 and a second blade body 2, respectively, to pivotably connect the first and second blade bodies 1 and 2 together. The through-holes 7 and 9 of the first and second blade bodies 1 and 2 have counterbores 4 and 5, respectively. A coil spring 6 wound around the pivot 3 is attached to the counterbore 4 of the first blade body 1. A ball bearing 8 is fitted in the counterbore 5 of the second blade body 2. The part of the through-hole 7 except the counterbore 4 has a square cross-section. The part of the through-hole 9 except the counterbore 5 has a circular cross-section.
The center of the pivot 3 serves as an angular shaft 3b with a square cross-section. When the pivot 3 is fitted into the through-holes 7 and 9, the angular shaft 3b is fitted in the angular part of the through-hole 7, which is the part except the counterbore 4. This pivotably integrates the pivot with the first blade body 1. On the other hand, the pivot 3 is loosely fitted in the circular part of the through-hole 9, which is the part except the counterbore 5. The pivot 3 is in contact with the inner circumferential face of the ball bearing 8. Then, the second blade body 2 is pivotable around the pivot 3.
A brim-like head 3a is provided at one axial end of the pivot 3. On the other hand, a screw 12 is screwed at the other axial end of the pivot 3. With the head 12a of the screw 12 being in contact with the inner race of the ball bearing 8 (i.e., pressing the inner race), the coil spring 6 comes into contact with the head 3a at one end and with the bottom of the counterbore 4 at the other end. This pressing force allows the portion of the first blade body 1 around the pivot to tightly abut on (or to be attached by the spring force to) the portion of the second blade body 2 around the pivot. As a result, the blades (i.e., blade edges) come into close contact with each other. Japanese Unexamined Patent Publication No. 2007-175203 (FIGS. 8 and 9) shows such a pivot structure of scissors including a coil spring.
In the pivot structure shown in FIG. 1, the angular shaft 3b of the pivot 3 is slightly loosely fitted in the angular part of the through-hole 7 of the first blade body 1. In opening and closing the scissors, as shown in FIG. 2, the first blade body 1 is thus inclined relative to the second blade body 2 such that the blades (i.e., the blade edges) move away from each other. For example, in the case of hairdressing scissors, hairs may be caught between the blades, thereby hindering smooth opening and closing and clean cutting of the scissors.
The present disclosure addresses the above-described problem of the pivot structure of the scissors including the coil spring as shown in FIG. 1.
In order to solve the above-described problem, the present disclosure provides a creative structure not to incline one blade body relative to the other blade body even if there is a gap between an angular part of a through-hole and an angular shaft.
Specifically, the present disclosure provides a pivot structure of scissors including first and second blade bodies each including a blade at one end side, and a finger ring at the other end side; and a pivot fitted in a through-hole formed in an intermediate portion of each of the first and second blade bodies to pivotably connect the first and second blade bodies together such that the both finger rings move to and away from each other to open and close the both blade bodies at the blades. The present disclosure has the following features.
Specifically, in a first aspect of the invention, a counterbore is formed around the through-hole of one of the blade bodies. Each of first and second brim-like heads is provided at an end of the pivot. A coil spring wound around the pivot is attached to the counterbore. With the first head being in contact with a peripheral edge of the through-hole of the other of the blade bodies, the coil comes into contact with the second head at one end and with a bottom of the counterbore at the other end. Pressing force of the coil spring allows the one of the blade bodies to tightly abut on the other of the blade bodies. A taper pressing part is formed at a blade body side of the second head to press and expand the one end of the coil spring radially outside the pivot.
According to a second aspect of the invention, in the first aspect of the invention, the pivot includes an angular shaft with a polygonal cross-section. A part of the through-hole of the one of the blade bodies except the counterbore is located to correspond to the angular shaft. The part has a polygonal cross-section corresponding to the cross-section of the angular shaft.
According to a third aspect of the invention, in the first or second aspect of the invention, a ring projection projects beyond a peripheral edge of the counterbore. The blade body side of the second head is pressed onto the ring projection.
According to a fourth aspect of the invention, in the third aspect of the invention, a cylindrical sleeve is fitted in the counterbore. A part of the sleeve projecting beyond the counterbore is the ring projection.
In the present disclosure, the coil spring attached to the counterbore is pressed and expanded radially outward by the taper pressing part of the pivot to be pressed onto the inner circumferential face of the counterbore. This integrates the pivot with the one blade body via the coil spring, thereby preventing or reducing backlash at the pivot and separation of the blades (i.e., the blade edges) in use of the scissors. In the case of hairdressing scissors, this prevents hairs from being caught between the blades in use to allow the user to smoothly handle the scissors and maintain clean cutting.
In the case of hairdressing scissors, each blade body often has a small thickness of about 3 mm, and each counterbore has a small depth of about 2 mm. However, the ring projection is formed along the peripheral edge of the counterbore, thereby increasing the depth. This increases the length of the coil spring, which can be included in the counterbore, to a desired length. In addition, the head of the pivot is pressed, thereby applying a concentrated load to the ring projection. The concentrated stress on the ring projection allows the blades to come into close contact with each other to reliably prevent or reduce uplifting of the blades.
Since the ring projection is the sleeve fitted and extending along the peripheral edge of the counterbore, the ring projection can be easily formed, and the height of the ring projection can be easily changed.